U.S. Pat. No. 4,584,686 discloses a Reed-Solomon (RS) error correction apparatus which is programmable to perform encoding, error detection and syndrome generation, in the manner hereinafter to be described, and uses one set of multiplier devices for computing check symbols and another set for computing error syndromes.
U.S. Pat. No. 4,804,959 discloses a method of increasing storage capacity in a disk file having one or more rotatable disks partitioned into concentric recording bands by using run-length-limited RS codes with code rates that increase progressively in each successive outer band. However, a separate encoder, each with a different polynomial, is required to implement each change in correction power.
U.S. Pat. No. 5,068,858 also discloses, for use with RS codes, a method for varying the error correction capability in a disk file having at least one disk partitioned into concentric recording bands by reducing the number of redundant bytes and hence codeword length in respective concentric bands of each disk progressively in each successive band toward the innermost band. The reduced codeword length may not, however, be compatible with the format of the written data sector.
These references and other prior art known to applicants do not disclose or remotely suggest a composite or unitary encoder/syndrome generator circuit that computes both check symbols and error syndromes using a single set of multiplier devices with varying tap weights having values that provide a maximum preselected error correction capability but readily adjustable, such as by programmable latches, to eliminate from the circuit selectable multiplier devices to reduce the error correction capability without requiring a change in the tap weight values.